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Detecting chilling tendency in series-manufactured cast iron components using micromagnetic test procedures

: Kröning, M.; Altpeter, I.; Laub, U.

Transactions of the American Foundrymen's Society 104 (1997), pp.1031-1038 : Ill., Lit.
ISSN: 0065-8375
Journal Article
Fraunhofer IZFP ()

During the past few decades, cast iron manufacturers have been confronted with the problem of the tendency to chilling in critical cast iron components. The tendency to chilling refers to an undesirable occurrence of ledeburitic and cementite phases in cast iron, which normally congeals as gray cast iron. Micromagnetic test procedures, like the analysis of the magnetic Barkhausen noise and the upper harmonics of the tangential magnetic field strength, are suitable for the nondestructive detection of the tendency to chilling, since they use the influence of specific microstructure states components on the remagnetization behavior of the material. Investigations on cylindrical specimens and step wedges, where these microstructure states, were specifically set for this purpose, are presented. The applicability of the procedures is tested, using series-manufactured cast iron components. Chilled microstructure states detected by means of micromagnetic procedures show good correspondence to metallographic results obtained at the same location. Based on these results, a prototype device for the detection of the tendency to chilling was developed. Thus, nondestructive testing (NDT) methods can be used to replace destructive testing of randomly selected reference samples, and components can be tested in-line.